porphyria

porphyria

[por-fēr´e-ah]

a genetic disorder characterized by a disturbance in porphyrin metabolism with resultant increase in the formation and excretion of porphyrins (uroporphyrin and coproporphyrin) or their precursors; called also hematoporphyria. Porphyrins, in combination with iron, form hemes, which in turn combine with specific proteins to form hemoproteins. hemoglobin is a hemoprotein, as are many other substances essential to normal functioning of the cells and tissues of the body.

Two general types are known: the erythropoietic porphyrias, which are concerned with the formation of erythrocytes in the bone marrow; and the hepatic porphyrias, which are responsible for liver dysfunction. Manifestations of porphyria include gastrointestinal, neurologic, and psychologic symptoms, cutaneous photosensitivity, pigmentation of the face (and later of the bones), and anemia with enlargement of the spleen. Large amounts of porphyrins are excreted in the urine and feces.

Treatment of this condition has been primarily symptomatic and varies in its effectiveness. Emphasis is on prevention of attacks by avoiding fasting and drugs that precipitate the symptoms. Photosensitivity may be controlled by avoiding exposure to light. Removal of the spleen is useful in some cases of the erythropoietic type of porphyria. Drug therapy includes the use of phenothiazines, chlorpromazine and promazine in particular. These drugs allay pain and nervousness and apparently allow a period of remission from symptoms. Meperidine hydrochloride (Demerol) may be given for pain and hydroxypheme (Hemetin) is given intravenously to compensate for genetic impairment of heme synthesis.

Patients with porphyria must not be given barbiturates, sulfonamides, alcohol, or chloroquine as these chemicals may precipitate or intensify attacks. It is recommended that persons with this disease carry with them at all times identification saying that they have porphyria so that in an emergency they will not be given medication that could precipitate an attack or even death.

acute intermittent porphyria (AIP) a hereditary, autosomal dominant, form of hepatic porphyria manifested by recurrent attacks of abdominal pain, gastrointestinal dysfunction, and neurologic disturbances, and by excessive amounts of δ-aminolevulinic acid and porphobilinogen in the urine; it is due to an abnormality of pyrrole metabolism. Called also intermittent acute porphyria.

congenital erythropoietic porphyria (CEP) a form of erythropoietic porphyria, with cutaneous photosensitivity leading to mutilating lesions, hemolytic anemia, splenomegaly, excessive urinary excretion of uroporphyrin and coproporphyrin, and invariably erythrodontia and hypertrichosis. Called also Günther disease.

porphyria cuta´nea tar´da (PCT) the most common form of porphyria, characterized by cutaneous photosensitivity that causes scarring bullae, discoloration, growth of facial hair, and sometimes sclerodermatous thickenings and alopecia; it is frequently associated with alcohol abuse, liver disease, or hepatic siderosis. Urinary levels of uroporphyrin and coproporphyrin are increased. There are two main types: an autosomal dominant (or familial ) form in which activity of the affected enzyme is reduced to half normal in liver, erythrocytes, and fibroblasts; and a sporadic (but probably also familial) form in which the reduction is confined to the liver. Both types are believed to be heterozygous and clinical expression occurs in adulthood, precipitated by disease or environmental factors. A more severe homozygous form begins in childhood and is called hepatoerythropoietic porphyria.

hepatoerythropoietic porphyria (HEP) a severe homozygous form of porphyria cutanea tarda believed to result from an autosomal dominant defect in the same enzyme as is affected in porphyria cutanea tarda; it is clinically identical to that disease but onset is in early childhood and enzyme activity in liver, erythrocytes, and fibroblasts is virtually absent.

porphyria variega´ta (variegate porphyria (VP)) a hereditary, autosomal dominant, type of hepatic porphyria characterized by chronic cutaneous manifestations, notably extreme mechanical fragility of the skin, particularly areas exposed to the sunlight, and by episodes of abdominal pain and neuropathy. There is typically an excess of coproporphyrin and protoporphyrin in the bile and feces.

por·phyr·i·a

(pōr-fir'ē-ă),

A group of disorders involving heme biosynthesis, characterized by excessive excretion of porphyrins or their precursors; may be inherited or acquired, as from the effects of certain chemical agents (for example, hexachlorobenzene).

porphyria

/por·phy·ria/ (por-fēr´e-ah) any of a group of disturbances of porphyrin metabolism characterized by increase in formation and excretion of porphyrins or their precursors.

acute intermittent porphyria (AIP) hereditary hepatic porphyria due to a defect of pyrrole metabolism, with recurrent attacks of abdominal pain, gastrointestinal and neurologic disturbances, and excessive amounts of δ-aminolevulinic acid and porphobilinogen in the urine.

congenital erythropoietic porphyria (CEP) a form of erythropoietic porphyria, with cutaneous photosensitivity leading to mutilating lesions, hemolytic anemia, splenomegaly, excessive urinary excretion of uroporphyrin and coproporphyrin, and invariably erythrodontia and hypertrichosis.

porphyria cuta´nea tar´da (PCT) a form characterized by cutaneous sensitivity that causes scarring bullae, hyperpigmentation, facial hypertrichosis, and sometimes sclerodermatous thickenings and alopecia; it is associated with reduced activity of an enzyme of heme synthesis.

variegate porphyria (VP) a hereditary hepatic porphyria, with chronic skin manifestations, chiefly extreme mechanical fragility of the skin, mainly of areas exposed to sunlight, episodes of abdominal pain, neuropathy, and typically an excess of coproporphyrin and protoporphyrin in bile and feces.

porphyria

(pôr-fîr′ē-ə)

n.

Any of several disorders of porphyrin metabolism, usually hereditary, characterized by the presence of large amounts of porphyrins in the blood and urine.

por·phyr′ic adj.

porphyria

[pôrfir′ē·ə]

Etymology: Gk, porphyros, purple

a group of inherited disorders in which there is abnormally increased production of substances called porphyrins. Two major classifications of porphyria are erythropoietic porphyria, characterized by the production of large quantities of porphyrins in the blood-forming tissue of the bone marrow, and hepatic porphyria, in which large amounts of porphyrins are produced in the liver. Clinical signs common to both classifications of porphyria are photosensitivity, abdominal pain, and neuropathy. See also acute intermittent porphyria,uroporphyria.

por·phyr·i·a

(pōr-fir'ē-ă)

A group of disorders involving heme biosynthesis, characterized by excessive excretion of porphyrins or their precursors; may be acquired, as from the effects of certain chemical agents (e.g., hexachlorobenzene), or inherited.

porphyria

Any of several inherited disorders in which substances called porphyrins accumulate in the body because of a deficiency of certain ENZYMES. Porphyrins are components formed in the course of the synthesis of HAEMOGLOBIN. The effects are numerous. There may be extreme sensitivity to sunlight, sweating, rapid heart rate, abdominal pain, vomiting, constipation, paralysis and other nervous system disturbances including psychotic disorders. In some cases the effects are mainly on the skin and include blistering, scarring and baldness, especially on exposure to light. Treatment is difficult and varies with the different types. Avoidance of sunlight is often important.

Porphyria

Any of a group of disturbances of porphyrin metabolism characterized by excess pophyrins (various biologically active compounds with a distinct structure) in the urine and by extreme sensitivity to light.

porphyria

a group of inherited or acquired diseases in which there are abnormalities of porphyrin metabolism, with accumulation in the tissues and increased excretion of porphyrins.

bovine congenital erythropoietic porphyria

inherited as an autosomal recessive trait in cattle; from birth, affected animals have varying degrees of reddish-brown discoloration of bones, teeth and urine, anemia and photosensitization, associated with a deficiency of the enzyme uroporphyrinogen III cosynthetase.

feline porphyria

inherited as an autosomal dominant trait; affected cats have discolored teeth, urine and tissues, severe anemia and photosensitivity associated with a deficiency of uroporphyrinogen III cosynthetase.

inherited porphyria

the disease is inherited in cattle and swine and is similar to erythropoietic porphyria of humans. There are excessive amounts of porphyrins in urine and deposits in the bones and teeth causing a dark red-brown discoloration. The animals are very photosensitive and cannot live outside. See also protoporphyria, hematoporphyrinuria, osteohematochromatosis.

pig porphyria

an erythropoietic porphyria, similar to bovine congenital erythropoietic porphoryia, but inherited as a dominant trait. Discoloration of the teeth, bones and tissues occurs, but not of the urine, except in severely affected cases. Photosensitization is not a feature. The enzymatic defect is unknown.

Patient discussion about porphyria

Q. I am 21 years old and have porphyira. I am in a crisis now. Its ruining my life. Please help!

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